Boise State University Theses and DissertationsCopyright (c) 2017 Boise State University All rights reserved.http://scholarworks.boisestate.edu/td
Recent documents in Boise State University Theses and Dissertationsen-usWed, 20 Dec 2017 08:19:02 PST3600Using Mountain Snowpack to Predict Summer Water Availability in Semiarid Mountain Watershedshttp://scholarworks.boisestate.edu/td/1328
http://scholarworks.boisestate.edu/td/1328Thu, 19 Oct 2017 14:24:16 PDT
In the mountainous landscapes of the western United States, water resources are dominated by snowpack. As temperatures rise in spring and summer, the melting snow produces an increase in river flow levels. Reservoirs are used during this increase to retain surplus water, which is released to supplement growing season water supply once the peak flows decrease to below water demands. Once there is no longer surplus natural flow of water, the water accounting changes – referred to as the day of allocation (DOA), and water previously retained within the reservoir is used to supplement the lower flow levels. The amount of water stored in the reservoir on the day of this accounting shift determines the water allocated to water right holders for the remainder of the water year. Predicting the day that allocated water will be determined is of special interest to both regulators and those that retain water rights per the Prior Appropriation Law. A method to forecast this day is developed using daily snow water equivalent data for the Boise, Payette, and Upper Snake Rivers in a multiple linear regression model. The melt rates of snowpack are typically comparable to using the maximum accumulation of that snowpack as predictor variables for day of allocation. Therefore, water users can be confident in predictions based on snowpack to determine what crops can be grown. The primary controls on these variances are water demand and volume of water accumulated.
]]>
Rebecca Dawn Garst<em>In Vitro</em> and <em>In Vivo</em> Studies of Chemotherapeutic Doxorubicin Analogshttp://scholarworks.boisestate.edu/td/1327
http://scholarworks.boisestate.edu/td/1327Fri, 13 Oct 2017 16:32:46 PDT
Anthracyclines remain widely prescribed and successful anticancer agents, despite serious side effects. Doxorubicin (DOX) is the most prominent anthracycline used to treat many cancers, including hematologic malignancies, soft-tissue sarcomas, cancers of the head and neck, and breast cancer. However, the clinical application of DOX is limited by the development of life-threatening cardiomyopathy and congestive heart failure. The main mechanisms of cardiotoxicity are thought to be mediated through the C-13 carbonyl and quinone ring structures in DOX. To improve the anticancer activity and reduce the cardiotoxic side effects of DOX, two synthetic analogs (GPX-150 and GPX-160) were developed and tested for in vitro and in vivo activity against a panel of soft tissue sarcoma cells. The analogs were further subjected to an array of tests to examine drug stability, transport properties, topoisomerase inhibitory activity and metabolism by cytochrome P450 enzymes.

The two analogs were effective anticancer agents against an array of cancer cells. In particular, GPX-160 exhibited in vitro cytotoxicity against human soft tissue sarcoma (STS) cells that was similar to DOX. Importantly, GPX-160 functioned equally well against both DOX-sensitive and DOX-resistant sarcoma cell lines, suggesting that its structural modifications allowed it to resist P-glycoprotein mediated drug efflux. Moreover, in a murine xenograft model of human STS, both GPX-150 and GPX-160 treatment resulted in significant decreases in both fibrosarcoma tumor volume and weight relative to the vehicle-treated controls.

The stability of the DOX analogs in tissue culture media suggest that in the absence of drug metabolizing enzymes, GPX-150 (t1/2 = 55.9 hr) will persist approximately 8-fold longer than DOX (t1/2 = 6.8 hr) and 3-fold longer than GPX-160 (t1/2 = 20.7 hr). In vitro drug absorption studies across Caco-2 cell monolayers indicate that GPX-150 and GPX-160 have higher permeability coefficients than DOX in both apical-to-basolateral and basolateral-to-apical directions. However, the transport of the analogs is not as heavily polarized in the basolateral-to-apical direction, as is seen with DOX. Both analogs also inhibited human topoisomerase IIα at low micromolar concentrations, supporting the possibility that they share a similar primary mechanism of action with DOX. Finally, human liver microsome metabolism of the two analogs showed that they were insensitive to aldo-keto reductase activity, which was expected based on the loss of the C-13 carbonyl and quinone structures. However, GPX-150 and GPX-160 remained sensitive to CYP2C8 and CYP3A4 activity.

Overall, these studies serve as an initial characterization of two DOX analogs that appear to hold great promise as a next generation of anthracyclines that overcome problems of drug resistance, while mitigating the cardiotoxicity that has limited the use of DOX.

]]>
Sangphil MoonThe “Other” and “I”: Patriarchal and Racial Violence via Postcolonial Theory in Toni Morrison’s <em>Jazz</em> and <em>Paradise</em>http://scholarworks.boisestate.edu/td/1326
http://scholarworks.boisestate.edu/td/1326Fri, 13 Oct 2017 16:32:42 PDT
By maintaining an “I”/“other” dynamic through the dehumanizing of the economically disadvantaged African American population, unequal distribution of wealth, lack of education and employment opportunity, and mass violence, the government creates an environment that leads to systemic violence within African American communities. This thesis asserts that Toni Morrison addresses this violence through a post-colonial theoretical lens, which incorporates both sexism and racism as a catalyst for destructive behavior by African Americans; a behavior which is established through imitation of dominant white violent actions. It does this through a study of the historical platform that Morrison’s Paradise (1997) is based upon and relates this historical violence to the novel’s moment of crisis, the massacre at the convent. Doing so develops the theory that the novel’s violence is the mimicry of colonial action. Supporting texts by Patricia Hill Collins, bell hooks, and Aimé Césaire assist in connecting violence to patriarchal sexism, racism, and post-colonial theory while Joseph Conrad’s Heart of Darkness (1899) and Morrison’s Jazz (1992) assist in the illustration of post-colonial movements and cycles of violence through comparative study with Paradise. Careful consideration is given to the role both Christian and Western African religions play in the formation of violence based on difference. Scholarship by Alfred J. Rabetau and La Vinia Delois Jennings establishes a Christian and African religious presence in African American history as well as it’s connection to Morrison’s novels.
]]>
Heather McBrideThe Random Graph and Reciprocity Lawshttp://scholarworks.boisestate.edu/td/1325
http://scholarworks.boisestate.edu/td/1325Fri, 13 Oct 2017 16:32:37 PDT
The theory of random graphs, that is graphs generated by some prescribed random process, gained popularity in the late 1950s and the level of interest has only increased since then. Random graphs on a countably infinite set of vertices is the subject of this thesis. We show that almost all graphs on countably many vertices are isomorphic to each other, implying that there is only one random graph, namely the random graph, on countably many vertices (up to isomorphism). We will survey some historical results concerning the random graph, present a number of its graph theoretic properties, as well as explicit examples based on familiar concepts.
]]>
Spencer M. NelsonIntegration of Medical and Dental Services: Case Study of the Terry Reilly Health Services Latah Clinic Experiencehttp://scholarworks.boisestate.edu/td/1324
http://scholarworks.boisestate.edu/td/1324Fri, 13 Oct 2017 16:32:33 PDT
Although evidence has demonstrated the link between oral and overall health, full integration of medical and dental services in practice is rare in the United States. The current research was designed to describe the development and implementation of the Terry Reilly Health Services (TRHS) Latah Medical-Dental-Behavioral Health integrated clinic (Latah Clinic). Data was collected through structured interviews with a purposive sample of employees from TRHS; observations of a Latah Clinic care team meeting; an environmental scan of facility space; and an analysis of intake forms used at the Latah Clinic. Seven employees from TRHS were invited to participate in structured interviews. Five participants completed the interviews, three face-to-face and two via e-mail. Checklists were developed to document evidence of integration during the Latah Clinic care team meeting, environmental scan and analysis of intake forms.

The findings from this study suggest that the Latah Clinic is fully integrated and demonstrates high levels of collaboration. The clinic would like to continue to grow and improve, therefore, suggestions to aide in this endeavor were provided. Study limitations such as small sample size and the lack of information from the perspective of the patient must be considered when interpreting the findings.

TRHS Latah Medical-Dental-Behavioral Health Clinic is a rarity in the United States. The strategies used in the TRHS integration process serve as a model for other practices and health care organizations as they evolve toward becoming patient-centered medical-dental homes.

]]>
Kylie B. PaceEarthquake Segment Boundaries and Tsunamigenic Faults of the Kodiak Segment, Alaska-Aleutian Subduction Zonehttp://scholarworks.boisestate.edu/td/1323
http://scholarworks.boisestate.edu/td/1323Fri, 13 Oct 2017 16:32:29 PDT
The most recent megathrust earthquake to impact the Alaska subduction zone was the M9.2 Great Alaska earthquake of 1964. This multi-segment rupture spanned over 700 km of the plate boundary and engendered both local and trans-Pacific tsunamis. The Kodiak Islands region served as the southwestern limit to rupture. The nature of past megathrust segmentation for the Alaska subduction zone has been largely hypothesized through paleoseismological methods and the Kodiak region in particular has not received a comprehensive geophysical characterization of its inferred segment boundaries.

I analyze multiple geophysical datasets (e.g. seismic reflection, earthquake, potential fields) to understand the spatiotemporal relationships between subduction, accretion, lower and upper plate structure, and tsunamigenic fault hazard in the context of the known megathrust earthquake record and other interseismic observations for the Kodiak region.

The northeast Kodiak segment boundary is defined by the subducting 58° fracture zone, which can be traced below the forearc using magnetic and gravitational fields. Subduction of this feature is expressed on post-1964 seismicity, is consistent with oblique shortening, and manifests itself within the upper plate as the Portlock Anticline.

The southwest segment boundary marks the transition between the Kodiak and Semidi segments. It is shown to be a region that shifts from significant margin erosion to a region of imbricate thrusting and margin growth. These two zones are bound by fracture zone subduction. I furthermore independently constrain and compliment paleoseismological models of joint Kodiak and Semidi segment rupture by identifying and characterizing a through-going marine fault zone across this segment boundary.

Finally, I revisit the source mechanisms for the local tsunami that inundated the Kodiak Islands as a result of the 1964 earthquake. I provide a new tsunamigenic source model that suggests discrete uplift of the Kodiak Islands shelf fault system and illuminate its along-strike rupture variability throughout the Holoecene epoch.

My findings suggest segment boundaries across Kodiak have a clear geophysical expression and a multi-dataset approach is necessary to decipher tectonic controls on megathrust segmentation.

]]>
Marlon D. RamosThe Evolution of Anti-Bat Sensory Illusions in Mothshttp://scholarworks.boisestate.edu/td/1322
http://scholarworks.boisestate.edu/td/1322Fri, 13 Oct 2017 16:32:25 PDT
Prey-generated illusions span sensory systems. Previous studies have mainly focused on visual illusions presented by prey coloring or morphology, but few have explored illusions produced via sound. We investigate an acoustic sensory illusion in moths, created by complex hindwing structures that divert echolocating bat predators. A phylogeny of the moth family, Saturniidae, in combination with data from geometric morphometrics, reveals that hindwings have repeatedly elongated to form tails across evolutionary time. Using high-speed, multi-camera, synchronized videos of bat-moth battles, we quantified the selective pressure of predation on extant and experimentally-modified moths, defined by moth escape success from bat attack. We approximated a gradient of less derived to more derived non-tailed Saturniidae morphs using Antheraea polyphemus, by reducing hindwing area (reduced), maintaining hindwing area (intact, sham) and adding hindwing area (elongated). We performed similar alterations along a potential evolutionary gradient with two tailed species, Actias luna and Argema mimosae, by removing the tails (ablated), shortening the tails (shortened, blunt), maintaining the tails (intact, sham) or elongating the tails (elongated, A. luna only). With increasing tail length, moths had a greater chance of surviving bat attack (model slope = 0.18±0.05) and the longest-tailed moths (tails > 7cm) survived bat attack in more than 56% of battles. Bat attack was also diverted from a moth’s body to its hindwing region at increasing rates with increasing hindwing length (model slope = 0.31±0.05). Tailed moths drew bat attack either towards the body or tail ends in 75% of interactions and towards the hindwing in only 25% of interactions, thus providing support for an attack on multiple targets, rather than the center of a single enlarged echo. We also extracted the 3D flight paths of moths from these encounters and found that flight kinematics do not change across genera or treatments, nor are they associated with escape success. These data provide evidence supporting a sonar-specific sensory illusion of multiple targets, and a challenge to the physiological limits of bat echolocation.
]]>
Juliette RubinWind Farm Power Prediction in Complex Terrainhttp://scholarworks.boisestate.edu/td/1321
http://scholarworks.boisestate.edu/td/1321Fri, 13 Oct 2017 16:32:20 PDT
There has been increasing interest in predicting the velocity field within wind farms in complex terrain for resource assessment, turbine siting, and power forecasting. These capabilities are made possible by advancements in computational speed from a new generation of computing hardware and numerical methods. The current thesis research focuses on two technical components to advance the current state in wind power forecasting. The first component is improved prediction of wind flow over complex terrain using the versatile immersed boundary method to represent surface boundary conditions on a fixed Cartesian mesh. The proposed approach embodies the law-of-the-wall for rough surfaces and produces good results for benchmark wind data for complex terrain. The second component is the implementation and validation of wind turbine wake models and a first-principle based method to predict available wind power. Actuator disk models with and without rotation are considered. The wake models are validated against data from a published wind tunnel experiment and full-scale field data from an operational wind farm. The power prediction method is compared against normalized power data from operational wind farms and other computational studies available in literature. The actuator disk model with rotation simulates wake velocity deficits with better accuracy than the non-rotational model. The proposed power prediction method shows agreement with standard energy assessment methods without any ad-hoc decisions. Finally, the computational capability is applied to a hypothetical wind farm in Southern Idaho to demonstrate its versatility.
]]>
Micah Sandusky<em>In Situ</em> TEM Micropillar Compression Testing in Irradiated Oxide Dispersion Strengthened Alloyshttp://scholarworks.boisestate.edu/td/1320
http://scholarworks.boisestate.edu/td/1320Fri, 13 Oct 2017 16:32:16 PDT
The objective of this study is to determine the validity of in situ transmission electron microscopy (TEM) micro-compression of pillars in as received and ion-irradiated Fe-9%Cr oxide dispersion strengthened (ODS) alloy. The growing role of charged particle irradiation in the evaluation of nuclear reactor candidate materials requires the development of novel methods to assess mechanical properties in near-surface irradiation damage layers just a few micrometers thick. In situ TEM mechanical testing is one such promising method, yet size effects must be understood to validate the technique. In this work, a micro-compression pillar fabrication method is developed. Yield strengths measured directly from TEM in situ compression tests are within expected values, and are consistent with predictions based on the irradiated microstructure. Measured elastic modulus values, once adjusted for deformation and deflection in the base material, are also within the expected range. A pillar size effect is only observed in samples with minimum dimension ≤ 100 nm due to the low inter-obstacle spacing in the as received and irradiated material. By comparing the microstructural obstacle spacing with specimen dimensions, size effects can be understood and TEM in situ micropillar compression tests can be used to quantitatively determine mechanical properties of shallow ion-irradiated layers.
]]>
Kayla Haruko YanoThe Mechanism of Radiation-Induced Nanocluster Evolution in Oxide Dispersion Strengthened and Ferritic-Martensitic Alloyshttp://scholarworks.boisestate.edu/td/1319
http://scholarworks.boisestate.edu/td/1319Fri, 13 Oct 2017 16:32:12 PDT
The objective of this study is to evaluate the mechanism of irradiation-induced nanoparticle evolution in a model Fe-9%Cr oxide dispersion strengthened steel and commercial ferritic-martensitic alloys HCM12A and HT9. Each alloy is irradiated with Fe2+ ions, protons, or neutrons to doses ranging from 1-100 displacements per atoms at 500°C. The morphology of nanoclusters are characterized using atom probe tomography. The evolution of clusters in each alloy are notably different with each irradiating particle, and the competing effects of ballistic dissolution and radiation-enhanced, diffusion-driven growth are attributed to the respective differences in cluster evolution. A phase evolution model, originally theorized by Nelson, Hudson, and Mazey, is used to simulate time-dependent nanocluster irradiation evolution in each alloy, with useful insights achieved to inform future alloy development. In all cases, a downward temperature shift is required to emulate low-dose-rate nanocluster evolution using higher-dose-rate irradiations.
]]>
Matthew John SwensonIdentification of Unknown Landscape Types Using CNN Transfer Learninghttp://scholarworks.boisestate.edu/td/1318
http://scholarworks.boisestate.edu/td/1318Fri, 13 Oct 2017 16:32:08 PDT
Unknown image type identification is the problem of identifying unknown types of images from the set of already provided images that are considered to be known, where the known and unknown sets represent different content types. Solving this problem has a lot of security applications such as suspicious object detection during baggage scanning at airport customs, border protection via remote sensing, cancer detection, weather and disaster monitoring, etc. In this thesis, we focus on identification of unknown landscape images. This application has a huge relevance to the context of a smart nation where it can be applied to major national security tasks such as monitoring the borders or the detection of unknown and potentially dangerous landscapes in critical locations.

We propose effective semi-supervised novelty detection approaches for the unknown image type identification problem using Convolutional Neural Network (CNN) Transfer Learning. Recently, the CNN Transfer Learning approach has been very successful in various visual recognition tasks especially in cases where large training data is not available. Our main idea is to use pre-trained CNNs (i.e. already trained on large datasets like ImageNet [10]) that are then used to train new models specifically applicable to the landscape image dataset. Features extracted from these domain-specific trained CNN are then used with standard semi-supervised novelty detection algorithms like Gaussian Mixture Model, Isolation Forest, One-class Support Vector Machines (SVM) and Bayesian Gaussian Mixture Models to identify the unknown landscape images.

We provide two fine-tuning approaches: supervised and unsupervised. Supervised fine-tuning approach simply uses the the class categories (landscape classes, e.g. airport, stadium, etc.) of the known images dataset. The unsupervised fine tuning approach on the other hand learns the class categories from the known images using the unsupervised clustering-based algorithm. We conducted extensive experiments that prove the effectiveness of our approaches. Our best values of AUROC and average precision scores for the identification problem are 0.96 and 0.94, respectively. In particular, we statistically prove that both fine-tuning methods significantly increase the performance of the identification with respect to the non fine-tuned CNN, and unsupervised and supervised fine tuning approaches are comparable.

]]>
Ashish SharmaLysenin Channels as Single Molecule Nano-Sensors and Nano-Switches for Controlled Membrane Permeabilityhttp://scholarworks.boisestate.edu/td/1317
http://scholarworks.boisestate.edu/td/1317Fri, 13 Oct 2017 16:32:03 PDT
Pore-forming toxins secreted by various evolutionarily distant organisms are important components of their innate defense mechanisms. These toxins may kill the target cells by inserting un-regulated channels into the plasma membrane. Tampering with the otherwise well-controlled membrane permeability alters cell homeostasis by contributing to un-controlled dissipation of both chemical and electrical gradients, which is often an essential component of virulence mechanisms leading to cell death. However, the same ability to create nanoscopic conducting pathways, i.e. nanopores, has been exploited for creating powerful tools in nano-biotechnology. Single nano-channels reconstituted in artificial planar lipid membranes are extremely versatile sensors that are capable of detection, identification, and characterization of single molecules. In addition, the changes in permeability induced by pore-forming toxins reconstituted in artificial and natural lipid membrane systems are exploited for numerous biomedical, scientific, and bio-technological applications. Many of these applications, underlying principles, and limitations are briefly described in the introduction section of this dissertation.

To overcome many of the restrictions presented by currently used pore-forming toxins, we propose to use lysenin channels for both stochastic sensing and for the achievement of controlled membrane permeability. Lysenin is a pore-forming toxin extracted from the earthworm E. foetida that inserts large nanopores in natural and artificial lipid membranes containing sphingomyelin. Chapter 2 of the presented work is focused on exploring the use of single lysenin nanopores for stochastic sensing of human angiotensin II, a short hormone peptide,which is highly relevant for the pathophysiology of cardiovascular diseases. Besides a traditional analysis of the interactions between lysenin channels and peptides, we succeeded to employ high sensitivity liquid chromatography – mass spectroscopy analyses to demonstrate the passage of un-altered peptide molecules through open lysenin channels.

In Chapter 3 we exploit the unique regulatory mechanisms presented by lysenin channels to achieve controlled permeability over artificial and natural lipid membranes. We demonstrate that ATP molecules may reversibly regulate the macroscopic ionic conductance of lysenin channels inserted into planar lipid membranes. Lysenin reconstitution into spherical membranes (liposomes) enables a two-way control over membrane permeability by using multivalent metal cations capable of inducing reversible ligand-induced gating of the channels. Live cell analyses demonstrate that lysenin channels allow transport of non-permeant molecules in Jurkat leukemia and ATDC5 chondrogenic cells. In addition, extended control over membrane permeability is achieved by using chitosan molecules as irreversible blockers of the macroscopic conductance. Survival rate estimations indicate that the permeabilized cells maintain a satisfactory viability rate for further use. Therefore lysenin may be used for the controlled transport of ions and molecules in living systems.

]]>
Nisha ShresthaHousing the Homeless: A Regional Analysis of the Impact of Available Beds on Rates of Homelessnesshttp://scholarworks.boisestate.edu/td/1316
http://scholarworks.boisestate.edu/td/1316Fri, 13 Oct 2017 16:31:58 PDT
The US Department of Housing and Urban Development has been collecting national data on the homeless population and the beds available to these individuals since 2007. This analysis utilizes those data by separating the United States into 11 regions and examining the impact of bed types on five demographics of the homeless population. This study finds that the impact of each bed type varies by region depending on these demographics. One striking finding is that while Safe Haven beds increase the homeless population in several regions, they cause a decrease in multiple homeless demographics in Region 6 [Prairie]. My analysis suggests some directions in policy making for reduction in homeless populations.
]]>
Cassandra Nicole SolmonsenExploring the Impact of Climate and Land Cover Change on Regional Hydrology in a Snowmelt-Dominated Watershed: The Upper Boise River Basin, Idahohttp://scholarworks.boisestate.edu/td/1315
http://scholarworks.boisestate.edu/td/1315Fri, 13 Oct 2017 16:31:54 PDT
Seasonally snow-dominated, mountainous watersheds supply water to many human populations globally. However, the timing and magnitude of water delivery from these watersheds has already and will continue to change as climate is altered. Associated changes in watershed vegetation cover further affect the runoff responses of watersheds, from altering evapotranspiration rates to changing surface energy fluxes, and there exists a need to incorporate land cover change in hydrologic modeling studies. However, few land cover projections exist at the scale needed for watershed studies, and current models may be unable to simulate key interactions that occur between land cover and hydrologic processes.

To help address this gap in the literature, we explored the impacts of climate and land cover change on hydrologic regimes in the Upper Boise River Basin, Idaho. Using a multiagent simulation framework, Envision, we built a hydrologic model, calibrated it to historic streamflow and snowpack observations, and ran it to year 2100 under six diverse climate scenarios. Under present land cover conditions, average annual discharge increased by midcentury (2040-2069) with 13% more runoff than historical (1950-2009) across all climate scenarios, with ranges from 6-24% of increase. Runoff timing was altered, with center of timing of streamflow occurring 4-17 days earlier by midcentury. Our modeled snowpack was more sensitive to warming at lower elevations, and maximum snow water equivalent decreased and occurred 13-44 days earlier by midcentury. Utilizing metrics applicable to local water managers, we see the date that junior water rights holders begin to be curtailed up to 14 days earlier across all models by the end of the century, with one model showing this could occur over a month earlier. These results suggest that current methods of water rights accounting and management may need to be revised moving into the future.

To test the sensitivity of our hydrologic model to changes in land cover, we selected a projected future land cover from the FORE-SCE (FOREcasting SCEnarios of land-use change) model. Our future land cover produced less evapotranspiration and more runoff, which stemmed from misclassification of high elevation regions between the FORE-SCE model and our initial land cover dataset, due to changes in the NLCD (National Land Cover Database) classification methodology. Additionally, FORE-SCE does not explicitly model wildfire or vegetative response to climate, both of which will likely be major drivers of landscape change in the mountainous, forested, western U.S., potentially making it insufficient for land cover projections in these areas. With evapotranspiration being the only parameter changing between land cover types in our hydrologic model, we were unable to capture the totality of hydrologic response to land cover change and other models may be better suited for such studies. This study highlights the necessity for better land cover projections in natural ecosystems that are attuned to both natural (e.g., climate, disturbance) and anthropogenic (e.g. management, invasive species) drivers of change, as well as better feedback in hydrologic models between the land surface and hydrological processes.

]]>
Amy SteimkeMulti-Rate Runge-Kutta-Chebyshev Time Stepping for Parabolic Equations on Adaptively Refined Mesheshttp://scholarworks.boisestate.edu/td/1314
http://scholarworks.boisestate.edu/td/1314Fri, 13 Oct 2017 16:31:49 PDT
In this thesis, we develop an explicit multi-rate time stepping method for solving parabolic equations on a one dimensional adaptively refined mesh. Parabolic equations are characterized by their stiffness and as a result are usually solved using implicit time stepping schemes [16]. However, implicit schemes have the disadvantage that they can be expensive in higher dimensions or complicated to implement on adaptive or otherwise non-uniform meshes. Moreover, for coupled systems of parabolic equations, it can be difficult to achieve the expected order of accuracy without using sophisticated operator splitting techniques. For these reasons, we seek to exploit the properties of stabilized explicit methods for parabolic equations. In particular, we use the Runge-Kutta-Chebyshev (RKC) methods, a family of explicit Runge-Kutta methods, with numerical stability regions that extend far into the left half plane [12, 15, 21, 22, 26, 27, 28].

A central goal of this thesis is to use a second order RKC scheme to numerically solve parabolic equations on a one dimensional adaptively refined finite volume mesh. To make our implementation efficient, we design a time stepping algorithm in which time step sizes are chosen to respect the local mesh widths. This time stepping process requires communication between the RKC stages on different refinement levels. By linearly interpolating in time between the stage values, we obtain the ghost cell values for the finite volume scheme on each level. To our knowledge, this approach to adaptively refining in time, commonly referred to as a "multi-rate time stepping" strategy, combined with RKC time stepping method has not been previously implemented.

We develop our multi-rate algorithm on a one dimensional statically refined mesh using the second order finite volume scheme to numerically solve the heat or diffusion equation on each grid stored in a hierarchy of meshes. Using the "method of manufactured solutions", we demonstrate that our method is second order accurate, and for our test problem, the multi-rate scheme requires only about 20% of the computational work required by the uniformly refined mesh at the same resolution.

The algorithm we develop manages the time stepping between the refinement levels only, and so extends directly to higher dimensional problems. Future work in this direction includes applying the new multi-rate RKC time stepping scheme to biological pattern formations or crystal growth in the 2D ForestClaw code [7] on parallel machines.

]]>
Talin MirzakhanianThe Other Side of the Atomic Air Force: Artifacts of the Air Force's People Programshttp://scholarworks.boisestate.edu/td/1313
http://scholarworks.boisestate.edu/td/1313Thu, 12 Oct 2017 17:17:15 PDT
From its inception recruitment and retention concerned Air Force leaders, more specifically Strategic Air Command (SAC) and Air Defense Command (ADC) leadership in the early years, and it continued as a recurring theme throughout the Air Force's very short lineage. Early Air Force leaders recognized a need for attracting the nation's most desirable and competent, as well as the need to retain those individuals for an extended amount of time. Recruiting methods that only targeted the Airmen quickly changed as Air Force leaders realized that the Air Force recruited Airmen, but retained families. Early airpower leaders, including SAC's longest serving commander General Curtis E. LeMay, thus offered benefits, or as many later labeled them, entitlements, to attract and retain the whole family. The majority of these programs for the Air Force originated in the late 1950s and matured during the mid- 1960s. Beyond recruitment, SAC’s “People Programs” contributed to the Air Force's integration process while building a foundation for race and gender equality. The creation of the Air Force's welfare programs, while successful, also created a slew of bills that leadership now struggles to pay.
]]>
Yancy D. MailesAn Intellectual Framework for Assessing Agricultural Climate Adaptation Combining Stakeholder Engagement and Process Based Modeling: Lower Boise River Basin, Idahohttp://scholarworks.boisestate.edu/td/1312
http://scholarworks.boisestate.edu/td/1312Wed, 11 Oct 2017 22:01:04 PDT
The impacts of climate change have significant implications for agricultural yields and water use. Previous studies have focused on impacts of climatic factors on crop phenology and yields, with little consideration of local farm management strategies that might mitigate some of these negative effects. Further, the inclusion of stakeholders is commonly left out of many biophysical studies of agricultural landscapes. Therefore, there is considerable uncertainty in the future of regional agroecosystems. In this study, we adopt a social-ecological systems perspective to develop an intellectual framework for assessing agricultural climate adaptation. With research questions focused in both biophysical and social science, we utilize a process-based crop simulation model and stakeholder meetings to examine agricultural response to climate change and adaptations that mitigate for climate change effects. This study advances our understanding of future climate effects on local agriculture, and provides a framework to include local variables into process-based modelling methods.

A regional assessment of baseline (1980–2015) and future (2015–2099) yields and water use for four irrigated crops in the Lower Boise River Basin (LBRB) of southwestern Idaho was conducted using a stakeholder informed model. Six different future climate scenarios, ranging in precipitation and temperature, were applied to our model to understand the potential degree to which climate change might affect yields, hydrologic fluxes, and planting date. Analysis of crop yields in most climate scenarios show a slight to moderate decrease in wheat and corn yields by 2100, while alfalfa and sugarbeets stay the same or moderately increase in more mild scenarios. Next, we identify potential concerns with the current irrigation season, which starts on April 1. Under all climate scenarios, our model predicts the growing season to start earlier in the year based on ET estimates and planting dates. This has major implications for future water policy, as the current irrigation season may need to be redefined to allow for early season irrigation in the coming decades. Our results, along with continued communication and iterative stakeholder engagement in the LBRB, can lead to adaptive solutions and policy changes in the agricultural sector. This research highlights the usefulness of combining local information with biophysical models that aim to understand agricultural systems, and can therefore be adjusted to other regions.

]]>
Andrea LeonardEditable View Optimized Tone Mapping For Viewing High Dynamic Range Panoramas On Head Mounted Displayhttp://scholarworks.boisestate.edu/td/1311
http://scholarworks.boisestate.edu/td/1311Wed, 11 Oct 2017 22:00:58 PDT
Head mounted displays are characterized by relatively low resolution and low dynamic range. These limitations significantly reduce the visual quality of photo-realistic captures on such displays. This thesis presents an interactive view optimized tone mapping technique for viewing large sized high dynamic range panoramas up to 16384 by 8192 on head mounted displays. This technique generates a separate file storing pre-computed view-adjusted mapping function parameters. We define this technique as ToneTexture. The use of a view adjusted tone mapping allows for expansion of the perceived color space available to the end user. This yields an improved visual appearance of both high dynamic range panoramas and low dynamic range panoramas on such displays. Moreover, by providing proper interface to manipulate on ToneTexture, users are allowed to adjust the mapping function as to changing color emphasis. The authors present comparisons of the results produced by ToneTexture technique against widely-used Reinhard tone mapping operator and Filmic tone mapping operator both objectively via a mathematical quality assessment metrics and subjectively through user study. Demonstration systems are available for desktop and head mounted displays such as Oculus Rift and GearVR.
]]>
Yuan LiEffect of Particle Size Distribution and Packing Characteristics on Railroad Ballast Shear Strength: A Numerical Study Using the Discrete Element Methodhttp://scholarworks.boisestate.edu/td/1310
http://scholarworks.boisestate.edu/td/1310Wed, 11 Oct 2017 22:00:53 PDT
Railroad infrastructure plays a significant role in sustaining the economy of a country, and facilitates fast, safe and reliable transportation of passengers as well as commodities. Significant capital investments are required for the construction and maintenance of a railroad network that is structurally and functionally adequate. The ballast layer is one of the main structural components of a conventional rail track system, and comprises coarse-grained unbound particles, often as large as in size. The ballast as a load-bearing layer resists train-induced stresses through particle-particle interaction. Accordingly, particle-size distribution and packing characteristics are important factors that govern the mechanical behavior of the ballast layer under loading. A well-performing ballast layer should ideally possess optimum drainage characteristics to ensure rapid removal of surface water and adequate shear strength to restrain the track against excessive movement under loading. In-depth understanding of different factors affecting ballast behavior can help reduce recurrent costs associated with ballast maintenance.

Conducting common shear strength tests on coarse-grained geomaterials such as railroad ballast, and performing parametric studies to quantify the effects of different material, specimen, and test parameters on shear strength properties is often not feasible in standard geotechnical engineering laboratories due to the significantly large specimen and test setup requirements. In such situations, the Discrete Element Method (DEM) that facilitates micromechanical analysis of particulate matter becomes a logical alternative. The primary objective of this research effort is to study the effects of particle-size distribution and packing characteristics on the shear strength behavior of railroad ballast. This was accomplished by simulating commonly used laboratory shear strength tests such as Direct Shear Test and Triaxial Monotonic Shear Strength Test using DEM. A commercially available three-dimensional DEM package (Particle Flow Code - PFC3D®) was used for this purpose. Published laboratory-test data were used to calibrate the numerical model. A series of parametric analyses were subsequently carried out to quantify the individual effects of different variables being studied on ballast shear strength behavior. In an effort to increase ballast shear strength through better packing within the granular matrix, a new gradation parameter, termed as the “Coarse-to-Fine (C/F) Ratio” was proposed. Changing the ‘coarse’ and ‘fine’ fractions within a particular gradation specification, the resulting effect on ballast shear strength was studied. In addition to studying the particle-to-particle interaction within the ballast matrix, this study also focused on studying the phenomenon of geogrid-ballast interaction under different packing conditions. A recently developed parameter known as the “Geogrid Gain Factor” was used to quantify the benefits of geogrid reinforcement of ballast. The ultimate objective was to further the understanding of ballast behavior under loading, which will ultimately lead to the design and construction of better-performing railroad tracks.

]]>
S. M. Naziur MahmudMicroscale Thermoelectric Property Characterization and Performance-Driven Thermoelectric System Designhttp://scholarworks.boisestate.edu/td/1309
http://scholarworks.boisestate.edu/td/1309Thu, 05 Oct 2017 14:55:10 PDT
Thermoelectric (TE) materials have promising energy-related applications, including waste heat recovery to improve energy efficiency in automobiles and industrial processes, energy harvesting to power remote sensors and devices, and power generation in radioactive environments like nuclear plants and space. Despite tremendous progress in TE material efficiency over the past few decades, the lack of effective TE property characterization methods and TE system design models remain two outstanding challenges in TE research. This thesis focuses on two important topics to address these challenges: (1) microscale characterization of TE material properties and (2) design and simulation of TE generators for waste heat recovery.

Scanning thermal microscopy (SThM) is a powerful tool for materials characterization. High-throughput SThM can greatly augment the value of combinatorial film studies by quickly mapping TE properties and identifying the optimal composition of a TE material system. The power of SThM is further amplified when multiple measurements, such as thermal conductivity and Seebeck coefficient, are obtained at the same time and same location with a single probe. While several probes for separate thermal and electrical measurements are available, unique challenges arise for combined microscale thermal and electrical measurements. Most TE materials develop nonconductive native oxide layers. Commercially available thermal AFM and SThM probes cannot establish electrical contact through these oxide layers, making combined electrical and thermal measurements impossible with conventional techniques. In this work, a novel thermal microprobe capable of simultaneous thermal conductivity and Seebeck coefficient measurements with minimal sample preparation is developed. New methods to measure the effective thermal contact radius and calculate the effective heat transfer coefficient in contact mode are introduced. The new probe can measure a wider range of thermal conductivity than its commercial counterpart with superior sensitivity. The probe is demonstrated with co-registered Seebeck coefficient and thermal conductivity on combinatorial films and materials with microscale radiation damage and native oxide layers.

The second part of the thesis addresses the thermal design and simulation of thermoelectric generators (TEGs). A high-temperature TEG that converts engine exhaust waste heat into electricity is modeled based on a light-duty passenger vehicle with a 4-cylinder gasoline engine. The model is validated by comparing simulation results to the experimental results of a TEG prototype tested on a diesel engine, and shows agreement within 3% for temperature distribution and 6% for pressure drop, respectively. Strategies to optimize TEG configuration and heat exchanger design for maximum fuel efficiency improvement are provided. Accounting for major parasitic losses, a maximum fuel efficiency increase of 2.5% is achievable using state-of-the-art nanostructured bulk half-Heusler thermoelectric modules.